Loans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized	$ 4,000	$ 4,000
Mortgage Loans Sold	86,491	177,509
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	15,462	38,332
Loans held in portfolio, net of unearned income	37,107,652	35,064,971
Non-accrual with no allowance	123,706	125,958
Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	15,160	37,345
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	313,220	341,279
Non-accrual with no allowance	124,000	126,000
Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,288,719	1,348,071
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	242,440	268,471
Loans held in portfolio, net of unearned income	593,220	626,082
GNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	6,783	2,488
FNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	8,377	34,857
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	8,114,183	7,695,917
Non-accrual with no allowance	67,245	84,797
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	79,340	86,416
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	798,130	859,537
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	207,317	241,422
Loans held in portfolio, net of unearned income	395,649	427,719
Mortgages | GNMA | Buy Back Option Program | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	$ 9,000	$ 11,000